Strength characterization of 3D hollow sandwich composite with Al-GF/PP faceplate under aerodynamic load

With the increasing speed of high-speed trains, especially when passing through tunnels or meeting cars, aerodynamic loads place higher demands on the strength characteristics of the skin structure. 3D hollow sandwich composite with thermoplastic aluminum alloy-glass fibre/polypropylene (Al-GF/PP) faceplate is a kind of sandwich material with fiber metal laminates as faceplate and 3D hollow composite as core material, which has the advantages of lightweight and high strength, sound and heat insulation, and can be used in the skin structure of high-speed train doors, skirts and so on. By comparing the performance of 3D hollow composites with different heights (10-25 mm) in flatwise compressive, edgewise compressive and flexural properties, it is found that the mechanical properties show a decreasing trend with the increase of the thickness, and the thicker 3D hollow composites have higher bending moments in the core and low structural stability. Aerodynamic load tests of 4 kPa, 5 kPa, 6 kPa and 7 kPa were carried out on the 3D hollow sandwich composite with Al-GF/PP faceplate. The results show that when the "8" fibres are subjected to forces perpendicular to the faceplate, the weft fibres carry the main load, which help to reduce the displacement of the fibres in the loading direction. The highest loading stress is applied at the joint between the core and the upper panel, and the main displacement occurs on the loaded side of the structure, with maximum displacement values of 1.80 μm, 2.26 μm, 2.72 μm, and 3.19 μm, respectively, and the aerodynamic loading of this order of magnitude does not lead to macroscopic deformation and failure of the specimens.